Plasmodium vivax has been considered for years as responsible for a mild form of malaria, due to the absence in the majority of its infections of the severe form of the disease, typical instead of the deadly human parasite P. falciparum. In the last decade, studies on vivax malaria have had a partial step ahead especially after the completion of the whole genome project, but there is still a gap of knowledge in the biology of this parasite. Moreover, the emergence of P. vivax antimalarial resistance in 1980s and its subsequent spread in the Southeast Asia have indicated new concerns about the possibility to control this parasite. P. vivax drug resistance poses a major threat to endemic countries and without important international efforts, we could assist in a near future to the paradox of seeing different malaria co-endemic countries, that have successfully controlled/eliminated P. falciparum, still fighting against P. vivax.